1. Field of the Invention
This invention relates to a mobile telephone device having an incoming call receiving function associated with a paging subsystem thereof.
2. Description of Background Art
FIG. 1 is a perspective view showing the external appearance of a conventional type of portable telephone set. FIG. 2 is a block diagram showing a circuit configuration of a conventional type of telephone set. In each of the figures, 101 denotes an antenna for transmitting or receiving an electromagnetic wave, 105 a CPU (a control part) for analyzing received data and controlling each of the blocks, 106, a memory for use with CPU 105, 107 a display part, 108 an operating part such as a keyboard, 109 a buzzer (a ringing element) for informing the presence of an incoming call to an operator, 152, 153 a receiving filter and a transmitting filter, respectively, connected to the antenna 101 for use in blocking a non-required band, 154 a receiving part for demodulating a high frequency signal to a base band signal, 155 a frequency synthesizer for applying a reference frequency to the receiving part 154 and a transmitting part 156 modulating the base band signal into a high frequency signal, 157 a data modulation/demodulation part for modulating a control signal of the base band signal demodulated by the receiving part 154 into a digital signal and modulating a digital signal to the base band signal, 158 a voice signal processing part for processing a voice signal for communication, 159 an ear piece (a voice output means) to cause an operator to listen sound, 160 a microphone through which an operator may input voice (voice input means), and 161 a battery (a power supplying means) acting as a power supply for each of the blocks.
An example of a mobile telephone device is "Personal Portable Cellular Telephone" Model 900, manufactured by Mitsubishi Electric Corporation.
FIG. 3 is a perspective view showing the external appearance of a conventional type of paging receiving device, and FIG. 4 is a block diagram for showing a circuit configuration of FIG. 3. In the figures, 201 denotes an antenna, 203 a receiving part for demodulating a high frequency signal into a base band signal, 204 a data demodulation part for demodulating a base band signal into a digital signal, 205 a CPU for analyzing the received data of the digital signal, 207 a displaying part, 208 an operating part, 209 a buzzer for informing the presence of a call to an operator, 210 a battery acting as a power supply for each of the blocks, and 211 is a DC/DC converter for converting an output voltage of the battery 210.
An example of a paging device is an "RDS FM pager type FR-50E (for Swedish System)" manufactured by Mitsubishi Electric Corporation.
The operation of each of the circuits of FIGS. 2 and 4 will now be described. First, an operation in which a portable telephone set is called up from a base station and the like will be described. A signal containing a call signal transmitted from the base station is received by the antenna 101. A required frequency band is filtered out from this signal by the receiving filter 152. Then, the receiving part 154 may use a tuning frequency supplied from the frequency synthesizer 155 to demodulate the filtered signal into a base band signal and output it to the data modulation/demodulation part 157. The data modulation/demodulation part 157 may demodulate the base band signal into a digital signal and then output it to the CPU 105. The CPU 105 may ring the buzzer 109 to call up the operator upon sensing a call signal in the digital signals.
When the operator acknowledges the sound of buzzer and depresses a transmitting key to the operating part 108, the CPU 105 may acknowledge this depressing action and initiate a return call via the base station. After this operation, the operator may use the microphone 160 and the ear piece 159 to communicate. During this period, the voice signal processing part 158 may process the voice signal, a voice signal inputted from the microphone 160 is outputted as a base band signal and the base band signal input from the receiving part 154 becomes a voice signal and is outputted to the ear piece 159. The transmitting part 156 and the receiving part 154 may perform a modulation and a demodulation between the base band signal and the predetermined frequency signal. The signal modulated at the transmitting part 156 is transmitted from the antenna 101 and the signal received at the antenna 101 is inputted to the receiving part 154. Under a waiting (standby) condition for receiving a call signal, power must be supplied from battery 161 to the receiving part 154, frequency synthesizer 155, data modulation/demodulation part 157, CPU 105, memory 106, displaying part 107, operation part 108 and buzzer 109.
The operation of the paging receiving machine shown in FIGS. 3 and 4 will now be described. With respect to the paging receiving machine, an example will be described in which the machine is operated by a voltage having an output voltage of battery 210 converted into a 5 V through DC/DC converter 211. In a similar manner as that of a portable telephone set, a signal sent from a base station, or the like, is passed through the antenna 201, receiving part 203 and data demodulation part 204 and then converted into a digital signal. After receiving the digital signal, the CPU 205 detects a call signal from a calling party and stores a message contained in the call signal into the memory 206, and at the same time, displays it at the display part 207. It further rings the buzzer 209 to call up the operator. The operator acknowledges the sound of the buzzer, looks at a message displayed at the displaying part, and can perform a corresponding countermeasure. For example, in case the message is a telephone number of a calling party, the operator can communicate with the party through another totally separate communication means, such as a public telephone system.
Since the conventional type of portable telephone set is constructed as above in FIG. 2, a power supply must always be supplied to the frequency synthesizer 155 in such a way that the operator can monitor the calling signal in a standby mode, resulting in substantial consumption of power during the waiting (standby) time, so the charge on battery 161 is depleted, shortening the operating time thereof.
Although the conventional type of paging receiving machine of FIG. 4 has a lower power consumption level and a longer operating time of the battery 210, as compared with that of the portable telephone set of FIG. 2, it has other disadvantages. For example, in the case where communication is required after being called up, a telephone number of called party displayed at the displaying part 207 of the paging receiving machine must be manually input into a separate telephone system to perform a communication, resulting in an inconvenience and so a long time passes before the communication is started.